(1) Field of the Invention
This invention is used in a typewriter or similar machine in which an input signal generates sound waves in an acoustic member which are then converted into electrical pulses for controlling various typewriter functions. In order to make certain that sound waves are generated only by the input signals, means are provided for insulating the acoustic member from sound wave producing vibrations which would otherwise occur as a result of typewriter operation.
(2) Description of the Prior Art
Among the prior art patents which disclose a device for protecting an acoustic element from external vibration is the patent of R. E. Franklin et al, U.S. Pat. No. 2,542,651. This patent discloses a first insulating material 2 which holds a crystal plate-like vibrating element 1. The insulating material 2 is held in place by metal springs 7 which are carried by supporting yoke 6 preferably formed of insulating material. Another such prior art patent is the patent of D. M. Kitterman, U.S. Pat. No. 2,802,955, which discloses a first insulating element comprising plate-like members 84 and 86 secured to a base slab 88 for mounting crystal element 10. A second insulating element, base plate 16, is also provided. Among the prior art patents which disclose spring supports for objects such as machinery, is the patent of A. Franceschetti, U.S. Pat. No. 2,702,703. This patent discloses in FIG. 5, for example, a spring support formed of a number of metal plates 9 and rubber elements 8 arranged in series. The patent of H. Krauss et al, U.S. Pat. No. 3,548,964, discloses means for limiting movement of an elastically suspended engine unit comprising a first rubber cushion 28 on which a frame 30 is mounted, and a member 22 which connects first rubber cushion 28 to a second rubber cushion 36, 37.
None of the aforementioned patents, however, disclose a device similar to the invention disclosed herein for protecting an acoustic element from external vibrations.